Service_area

syntax

service_area(F1, F2, dijkstra/traceback)

definition

service_area(F1, F2, dijkstra/traceback) calculates service areas for nodes in the network.

A service area is defined as the relation to the nearest destination node for each node in the node set. The results are based on the results of dijkstra calculations.

The service_area function requests three arguments:

F1: relation to the first node of a linkset;
F2: relation to the last node of a linkset;
dijkstra/traceback: the traceback item, a generated subitem by the dijkstra function.

description

The function results in a relation to the nodes in the nodeset. Use the lookup function to relate these numbers to the origin locations (see example).

applies to

attributes F1, F2 and dijkstra/traceback with uint32 value-type

conditions

The domain units of attributes F1 and F2 must match.

example

attribute<meter>       dist           (nodeset) := dijkstra(dist, F1, F2, nr_DestNode);
attribute<destination> servicearea_ns (nodeset) := 
   rlookup(
      service_area(
          F1 
         ,F2
         ,dist/TraceBack
       )
       , nr_DestNode
   ); 
attribute<destination> servicearea (origin) := servicearea_ns[nr_OrgNode];

F1	F2
8	7
1	4
16	15
2	3
5	4
6	7
9	10
12	11
14	15
18	20
19	17
3	0
4	11
7	1
10	3
11	13
13	17
15	10
20	21
17	20

domain linkset, nr of rows = 19

nr_DestNode
14
6
2
19

domain destination, nr of rows = 5

servicearea
0
1
2
3
1

domain origin, nr of rows = 5

F1	F2
8	7
1	4
16	15
2	3
5	4
6	7
9	10
12	11
14	15
18	20
19	17
3	0
4	11
7	1
10	3
11	13
13	17
15	10
20	21
17	20

F1	F2
8	7
1	4
16	15
2	3
5	4
6	7
9	10
12	11
14	15
18	20
19	17
3	0
4	11
7	1
10	3
11	13
13	17
15	10
20	21
17	20

F1	F2
8	7
1	4
16	15
2	3
5	4
6	7
9	10
12	11
14	15
18	20
19	17
3	0
4	11
7	1
10	3
11	13
13	17
15	10
20	21
17	20